Explain how anthropogenic changes in atmospheric composition are responsible for global warming?

Answer 1

The greenhouse effect has been keeping the Earth warm enough for human life since its beginnings. Infrared radiation comes from the sun into our atmosphere. The greenhouse gases of water vapor, carbon dioxide (CO2), methane and ozone (and a few others) prevent some of this heat reflecting back into space, thus keeping the planet warm.

However, since the 18th century, when we began to build factories, invent vehicles and produce electricity, humankind has been slowly putting more and more CO2 into the atmosphere. Every time we burn coal, gas or oil we increase the amount of greenhouse gases.

Forests too, which absorb carbon dioxide, have been cut down, and are still being cut down, all over the planet. With fewer trees, more of the CO2 goes into the atmosphere.

In 1800 the world population was less than one billion. Today it is close to 7 billion. Seven billion people wanting food, water and electricity and a share in the good life make a colossal demand on the resources of our planet.

So the increased greenhouse gases keep in more of the sun's heat. Global warming!